1. Field of the Invention
The present invention relates to a heat preservation and temperature increasing equipment, and in particular, to a constructed wetland wastewater treatment equipment under low temperature for continuous operation.
2. Description of the Related Art
Environment, especially temperature, prominently influences removal efficiency of contaminants by constructed wetlands. Shihe Wang et al have found that a removal rate of TP (total phosphorus) by the constructed wetlands in winter is about 15% lower than a removal rate of TP by the constructed wetlands in summer. HuanShen et al have found in a demonstration project, in which scenic water body is purified by a subsurface flow type constructed wetland, that mean removal rates of TP and TN (total nitrogen) by the winter wetlands are 34% and 27% lower than those of TP and TN by the summer wetlands, respectively. Wallace et al considers that an over-low temperature not only affects an effect of contamination treatment by the constructed wetlands, but also may cause several disadvantageous effects, such as, freezing of a substrate layer, low concentration of the bed, pipe fracture and so on, thereby restricting application of the constructed wetlands in winter in cold regions. The current studies of wetland heat preservation drop behind since various methods cannot produce desirable effect.